Methods and apparatus for assembling a low noise ejector motive nozzle

ABSTRACT

A method of assembling an ejector is provided, wherein the method includes providing a motive nozzle tip having a centerline axis and including a nozzle tip edge having at least one protrusion extending through a plane substantially normal to the centerline axis. The method also includes coupling the motive nozzle tip to the ejector.

BACKGROUND OF THE INVENTION

This invention relates generally to ejectors, and, more particularly, toan ejector motive nozzle that may be used in pumping, compression, ormixing applications.

At least some known ejectors mix two flow streams, a high-pressure(“motive”) stream and a low-pressure (“suction”) stream, so as toproduce a discharge flow with pressure intermediate to or lower than thetwo input flows. The ejector motive nozzle facilitates this mixingprocess by accelerating the high-pressure motive flow, thereby creatinga high speed jet that is channeled through a mixing tube or chamber toentrain the low pressure suction flow. The two mixed flows are thendischarged, typically through a diffuser.

Some known ejectors use a motive nozzle that is surrounded by a casingand includes a nozzle tip having a round or rectangular cross-sectionoriented about an axis of the ejector. At least some known nozzles maycreate a motive jet that oscillates in a bending mode, producingcoherent flow disturbances such as partial ring vortex structures at anedge of the jet. When these coherent flow disturbances strike adownstream wall of the casing, reflected acoustic waves may be producedand feedback towards the nozzle. The feedback waves may reinforce thejet bending oscillations and result in a fluid dynamic resonance thatmay produce damaging structural loads and/or high noise levels withinthe ejector. Over time, fluctuating loads produced by this fluid dynamicresonance may decrease the lifespan of the ejector or other hardware,add to maintenance costs, and/or create objectionable levels ofenvironmental noise.

BRIEF DESCRIPTION OF THE INVENTION

In one aspect, a method of assembling an ejector is provided, whereinthe method includes providing a motive nozzle tip having a centerlineaxis and including a nozzle tip edge having at least one protrusionextending through a plane normal to the centerline axis. The method alsoincludes coupling the motive nozzle tip to the ejector.

In another aspect, an ejector is provided, wherein the ejector includesa motive nozzle tip having a centerline axis and including a nozzle tipedge having at least one protrusion extending through a plane normal tothe centerline axis.

In a further aspect, a gas turbine engine is provided, wherein the gasturbine engine includes a compressor and an ejector coupled in flowcommunication with and configured to receive air bled from thecompressor. The ejector includes a motive nozzle tip having a centerlineaxis and including a nozzle tip edge having at least one protrusionextending through a plane normal to the centerline axis.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a cross-sectional schematic illustration of an exemplary gasturbine engine;

FIG. 2 is a schematic block diagram of the engine shown in FIG. 1 andincluding a turbine cooling ejector;

FIG. 3 is an enlarged schematic illustration of the turbine coolingejector shown in FIG. 2;

FIG. 4 is a perspective view of an exemplary nozzle tip that may be usedwith the turbine cooling ejector shown in FIG. 3; and

FIG. 5 is a perspective view of an exemplary cooling jet streamdischarged from the nozzle tip shown in FIG. 4.

DETAILED DESCRIPTION OF THE INVENTION

FIG. 1 is a schematic illustration of an exemplary gas turbine engine100. Engine 100 includes a compressor 102 and a combustor assembly 104.Combustor assembly 104 includes a combustor assembly inner wall 105 thatat least partially defines a combustion chamber 106. Combustion chamber106 has a centerline 107 that extends therethrough. In the exemplaryembodiment, engine 100 includes a plurality of combustor assemblies 104.Combustor assembly 104, and, more specifically, combustion chamber 106is coupled downstream from and in flow communication with compressor102. Engine 100 also includes a turbine 108 and a compressor/turbineshaft 110 (sometimes referred to as rotor 110). In the exemplaryembodiment, combustion chamber 106 is substantially cylindrical and iscoupled in flow communication with turbine 108. Turbine 108 is rotatablycoupled to, and drives, rotor 110. Compressor 102 is also rotatablycoupled to shaft 110. The present invention is not limited to any oneparticular engine and may be implanted in connection with other enginesor other devices which employ ejectors in any part of the processes bywhich they operate. For example, the present invention may be used with,but is not limited to use with oil refinery devices, chemical plantdevices, and electric cars.

In operation, air flows through compressor 102 and a substantial amountof compressed air is supplied to combustor assembly 104. Assembly 104 isalso in flow communication with a fuel source (not shown in FIG. 1) andchannels fuel and air to combustion chamber 106. In the exemplaryembodiment, combustor assembly 104 ignites and combusts fuel, forexample, synthetic gas (syngas) within combustion chamber 106 thatgenerates a high temperature combustion gas stream (not shown in FIG.1). Alternatively, assembly 104 combusts fuels that include, but are notlimited to natural gas and/or fuel oil. Combustor assembly 104 channelsthe combustion gas stream to turbine 108 wherein gas stream thermalenergy is converted to mechanical rotational energy.

FIG. 2 is a schematic block diagram of engine 100 including a turbinecooling ejector 150 coupled in flow communication between compressor 102and turbine 108. Low-pressure air is extracted from compressor 102 froma plurality of outlets 152 and high-pressure air is extracted from aplurality of outlets 154. In the exemplary embodiment, low-pressure airis extracted from the ninth stage of compressor 102 and high-pressureair is extracted from the thirteenth stage of compressor 102. Inalternative embodiments, low-pressure air may be extracted at anycompressor low-pressure stage and high-pressure air may be extractedfrom any compressor high-pressure stage.

The high-pressure and low-pressure air is channeled to ejector 150.Specifically, high-pressure air is channeled axially through a motivenozzle (not shown) within ejector 150, and low-pressure air is channeledto a chamber (not shown) surrounding the motive nozzle. As high-pressureair is discharged from the motive nozzle, it entrains the low-pressureair, to facilitate mixing between the two air flows. The mixed air flowis discharged to turbine 108 wherein the air facilitates cooling turbine108. As such, ejector 150 facilitates cooling turbine 108 usinglow-pressure air, such that the efficiency of engine 100 is improved ascompared to systems using high-pressure cooling air.

FIG. 3 is an enlarged schematic illustration of ejector 150. FIG. 4 is aperspective view of an exemplary motive nozzle tip 200 that may be usedwith ejector 150. FIG. 5 is a perspective view of an exemplary coolingjet 202 discharged from nozzle tip 200. Ejector 150 includes a motivenozzle 204 and a casing 206 that extends radially outward from adownstream end 208 of motive nozzle 204. Motive nozzle 204 includes asubstantially annular body portion 210 and a tapered conical portion 212extending from downstream end 208. Nozzle tip 200 extends fromdownstream end 208 with a frusto-conical cross-sectional shape, suchthat motive nozzle body portion 210 has a larger radius R₁ than a radiusR₂ of nozzle tip 200. Body portion 210 also includes a high-pressureinlet 214.

Casing 206 includes a substantially annular body portion 216 that isspaced radially outward from motive nozzle downstream end 208, such thata low-pressure chamber 218 is defined therebetween. A frusto-conicalportion 220 extends downstream from casing body portion 216. Portion 220is positioned such that low-pressure chamber 218 is coupled in flowcommunication with a chamber 222 defined by conical portion 220.Furthermore, a substantially annular mixing channel 224 is coupled inflow communication with, and downstream from, conical portion 220.Mixing channel 224 has a radius R₃ that is smaller than a radius R₄ ofcasing body portion 216. An ejection end 226 of ejector 150 is definedat a downstream end 228 of casing 206. Furthermore, casing body 216includes a low-pressure inlet 230.

The cross sectional area of nozzle tip 200 is convergent in thedirection of flow and, in the exemplary embodiment, includes a pluralityof protrusions 232 that extend substantially axially therefrom to definea nozzle lip 234. In the exemplary embodiment, protrusions 232 areidentical and each has a substantially triangular shape. Protrusions 232extend circumferentially about nozzle tip 200, such that a plurality oftriangular recesses 236 are defined between each pair ofcircumferentially-adjacent protrusions 232. Specifically, protrusions232 define a chevron-shaped nozzle lip 234 at an end of nozzle tip 200.In an alternative embodiment, nozzle tip 200 is slotted and includes aplurality of protrusions extending from a nozzle lip defined at an edgeof the slotted nozzle tip. Protrusions 232 may be rounded such thatnozzle tip 200 includes a plurality of round-edged cutouts. Moreover,although only seven protrusions 232 are illustrated, it should be notedthat nozzle tip 200 may include more or less protrusions 232. Inaddition, the size, shape, number, and relative orientation ofprotrusions 232 is variably selected depending on the use of nozzle tip200 to facilitate optimizing jet flow 238 discharged therefrom. Morespecifically, protrusions 232 and, more particularly, nozzle lip 234facilitate creating a jet flow discharged therefrom with lobed-shapedvortices 240, for example, a lobed-shaped jet 202.

During operation, high-pressure air is channeled to ejector 150 and isdischarged through inlet 214 into motive nozzle 204. Air at relativelylow pressure is discharged through low pressure inlet 230 into lowpressure chamber 218. The high-pressure air flows substantially axiallythrough motive nozzle 204 and is accelerated to high speed prior tobeing discharged through nozzle tip 200. The orientation of protrusions232 facilitates discharged air from nozzle tip 200 creating lobed-shapedjet 202. The shape, velocity, and pressure of lobed-shaped jet 202facilitates jet 202 entraining the low-pressure air in low-pressurechamber 218 causing the high-pressure and low-pressure air to mix inmixing channel 224. The mixed air is then discharged through ejector end226, such that the mixture of high-pressure and low-pressure air isutilized to facilitate cooling turbine 108. In alternative embodiments,the mixed air may be used to cool other components of engine 100.

The nozzle tip is configured to facilitate the formation of longitudinalflow structures (such as lobes or counter-rotating vortices) thatstabilize the jet. Furthermore, the nozzle tip is configured to resistformation of other destabilizing flow structures (such as ring vortices)when the jet is perturbed by noise or other flow disturbances.Specifically, during engine operations, the lobed-shaped jet 202 createdby protrusions 232 facilitates increasing the life-span of ejector 150.Specifically, the protrusions 232 facilitate reducing the intensity andsymmetry of flow disturbances produced by or associated with jet bendingoscillations, such as coherent ring vortices. Typically, jet bendingoscillations in an ejector cause acoustic waves to reflect off a casingwall and back towards the motive nozzle. The lobes created in jet 202 byprotrusions 232 reduce the coherency of circumferential turbulent flowstructure produced by jet bending, interfering with reinforcement ofsuch flow structures by acoustic waves reflected from casing 206.Furthermore, because the nozzle interior trailing edges produced byprotrusions 232 lie outside of a plane normal to the nozzle, the abilityof reflected acoustic waves to excite further jet bending oscillation isreduced. Specifically, protrusions 232 facilitate preventing a reflectedwave from oscillating in phase with oscillations of jet 202, such thatthe oscillations are disrupted and not enhanced. As such, protrusions232 facilitate disrupting both the formation and excitation of jetbending oscillations, and thereby, facilitate reducing the effects thatjet bending oscillations may have on ejector 150.

As a result of protrusions 232, less vibration is induced to ejector 150by jet bending oscillations as flow is discharged from nozzle tip 200.Furthermore, nozzle tip 200 and, more particularly, protrusions 232,facilitate reducing the excitation of any resonance and vibrationsinduced to ejector 150. Accordingly, ejector 150 generates substantiallyless noise, and experiences substantially reduced fluctuating structuralloads than other known ejectors. As such, a useful life of ejector 150and other connected devices is facilitated to be enhanced, andenvironmental noise produced by the ejector is reduced.

The above-described methods and apparatus facilitate increasing the lifespan of an ejector and reducing environmental noise produced by itsoperation. Specifically, the chevron-shaped nozzle tip produces alobed-shape jet that facilitates reducing jet bending oscillations whichmay occur in an ejector motive nozzle. Furthermore, the lobed-shaped jetfacilitates reducing the excitation of jet bending oscillations, suchthat vibrations induced to the ejector motive nozzle are reduced.Subsequently, less noise and fewer structural loads are generated withinthe ejector. Moreover, the chevron-shaped nozzle tip also increasesentrainment of the low-pressure air, allowing the ejector to operatemore efficiently. Ultimately, the above-described methods and apparatusfacilitate providing a more efficient and more stable ejector, such thatsystem engine efficiency may increase, costs associated with maintenanceof the ejector and devices in flow communication with the ejector maydecrease, and the life-span of the system may increase.

As used herein, an element or step recited in the singular and proceededwith the word “a” or “an” should be understood as not excluding pluralsaid elements or steps, unless such exclusion is explicitly recited.Furthermore, references to “one embodiment” of the present invention arenot intended to be interpreted as excluding the existence of additionalembodiments that also incorporate the recited features.

Although the apparatus and methods described herein are described in thecontext of an ejector motive nozzle for a gas turbine engine, it isunderstood that the apparatus and methods are not limited to ejectormotive nozzles or gas turbine engines. Likewise, the ejector motivenozzle components illustrated are not limited to the specificembodiments described herein, but rather, components of the ejectormotive nozzle can be utilized independently and separately from othercomponents described herein.

While the invention has been described in terms of various specificembodiments, those skilled in the art will recognize that the inventioncan be practiced with modification within the spirit and scope of theclaims.

What is claimed is:
 1. A method of assembling an ejector, said methodcomprising; providing a motive nozzle tip having a centerline axis andincluding a chevron-shaped nozzle tip edge having at least oneprotrusion extending through a plane substantially normal to thecenterline axis, the motive nozzle tip having a frusto-conical portionthat is downstream from a tapered conical portion of a motive nozzle,wherein the frusto-conical portion tapers at a first angle with respectto the centerline axis and the tapered conical portion tapers at asecond angle with respect to the centerline axis, the first angle beingdifferent than the second angle; configuring the motive nozzle tip toproduce lobed-shaped vortices in a stream discharged therefrom; andcoupling the motive nozzle tip to the ejector, such that the motivenozzle tip is positioned within an ejector casing that includes alow-pressure chamber and an annular mixing channel defined therein,wherein the annular mixing channel is downstream from the low-pressurechamber.
 2. A method in accordance with claim 1 further comprisingconfiguring the motive nozzle tip to facilitate reducing jet bendingoscillations in a stream discharged therefrom.
 3. A method in accordancewith claim 1 further comprising configuring the motive nozzle tip tofacilitate preventing a feedback wave from exciting coherent flowstructures within a jet discharged from the motive nozzle tip.
 4. Anejector comprising a motive nozzle tip having a centerline axis andcomprising: a frusto-conical portion that is downstream from a taperedconical portion of a motive nozzle, wherein said frusto-conical portiontapers at a first angle with respect to the centerline axis and saidtapered conical portion tapers at a second angle with respect to thecenterline axis, the first angle being different than the second angle;and a chevron-shaped nozzle tip edge comprising at least one protrusionextending through a plane substantially normal to the centerline axis,said motive nozzle tip is positioned within an ejector casing thatincludes a low-pressure chamber and an annular mixing channel definedtherein, and is configured to produce lobed-shaped vortices in a jetdischarged therefrom, wherein the annular mixing channel is downstreamfrom the low-pressure chamber.
 5. An ejector in accordance with claim 4wherein said motive nozzle tip is configured to facilitate reducing jetbending oscillations in a jet discharged therefrom.
 6. An ejector inaccordance with claim 4 wherein said motive nozzle tip is configured tofacilitate preventing a feedback wave from exciting jet bendingoscillations within a jet discharged from said motive nozzle tip.
 7. Agas turbine engine comprising: a compressor; and an ejector coupled inflow communication with said compressor and configured to receive airbled therefrom, said ejector comprising: a casing that includes alow-pressure chamber and an annular mixing channel; and a motive nozzletip having a centerline axis and comprising a frusto-conical portionthat is downstream from a tapered conical portion of a motive nozzle,wherein said frusto-conical portion tapers at a first angle with respectto the centerline axis and said tapered conical portion tapers at asecond angle with respect to the centerline axis, the first angle beingdifferent than the second angle, said motive nozzle tip furthercomprising a chevron-shaped nozzle tip edge having at least oneprotrusion extending through a plane substantially normal to thecenterline axis, said nozzle tip positioned within said casing andupstream from said annular mixing channel, wherein said motive nozzletip is configured to produce lobed-shaped vortices in a jet dischargedtherefrom.
 8. A gas turbine engine in accordance with claim 7 whereinsaid motive nozzle tip is configured to facilitate reducing jet bendingoscillations in a jet discharged therefrom.
 9. A gas turbine engine inaccordance with claim 7 wherein said motive nozzle tip is configured tofacilitate preventing a feedback wave from exciting jet bendingoscillations within a jet discharged from said motive nozzle tip.